fix isse with negativ lags (leads)
- add timeseries plots
- fix broadcasting issues
- adding accessors
- adding timeseries transformation functions (lag, lead, align)
- Moving project from https://git.dynare.org/DynareJulia/TimeDataFrames.jl to https://github.com/DynareJulia/TimeDataFrames.jl
- Adding project to Julia's General Registry